Flexible semiaromatic polyamides with a low moisture uptake

ABSTRACT

The present invention relates to a flexible semiaromatic polyamide composition with a low moisture uptake, made up by weight, the total being 100:
     A) 60 to 99.5% (preferably 70 to 93%) of at least one copolyamide of formula X/Y,Ar in which there are between 0.5 and 0.7 mol of X per 1 mol of Y, and in which
       Y denotes the residues of 1,10-decanediamine,   Ar denotes the residues of terephthalic acid,   X denotes the residue of aminoundecanoic acid NH 2 —(CH 2 ) 10 —COOH, the unit Y,I residue from the condensation of the diamine (Y) with isophthalic acid, wherein said composition is a flexible semiaromatic copolyamide;   
       B) 0.5 to 40% (preferably 7 to 30%) of at least one product chosen from plasticizers, nanofillers, polyolefins, crosslinked polyolefins and additives.

This application claims benefit, under U.S.C. §119(a) of French NationalApplications Number 03.09641, filed Aug. 5, 2003, and 04.00906, filedJan. 30, 2004; and also claims benefit, under U.S.C. §119(c) of U.S.provisional application 60/523,480, filed Nov. 19, 2003 This applicationis a divisional application of, and claims benefit to U.S. Ser. No.10/909,503, filed Aug. 2, 2004.

FIELD OF THE INVENTION

The present invention relates to flexible semiaromatic polyamides with alow moisture uptake. These polyamides also have good elongationproperties. These polyamides have a high thermomechanical strength.Polyamide-6 and polyamide-6,6 have high melting points but theirconversion is difficult and, furthermore, their water uptake is toohigh, which is damaging to their mechanical properties and to theirresistance to ageing. Furthermore, they are too rigid to be used aspipes; it is then necessary to render them flexible with plasticizers orimpact modifiers. All the properties are then lost. Polyamide-12 andpolyamide-11 are much used in the automobile industry because of theirnoteworthy mechanical properties, their ease of use and their resistanceto ageing. However, their thermomechanical strength is inadequate beyonda working temperature of 160° C. The invention relates to polyamideswhich are to replace polyamide-12 and polyamide-11 but which have animproved thermomechanical strength while retaining their ease ofconversion and their flexibility.

BACKGROUND OF THE INVENTION

There exist terephthalic copolyamides based on a 6 unit (for example,6,6/6,T or 6/6,T or also 6,I/6,T, comprising predominantly 6,T) whichhave very high melting points, above 300° C. These products are veryrigid and their elongation at break is less than 10%, which preventsthem from being used in the field of extrusion of pipes. Patent EP 550314 gives examples of copolyamides-12/6,T. U.S. Pat. No. 3,843,611discloses copolyamides-12,12/12,T. U.S. Pat. No. 5,708,125 disclosescopolyamides-10,6/10,T. None of these prior arts discloses a possibleaptitude with regard to ageing. Furthermore, none of these prior artsdiscloses the need for flexible polyamides. The aim of the presentinvention is to find polyamides which have resistance to ageing whenthey are subjected to a high working temperature, while remainingflexible. Such compositions have now been found.

SUMMARY OF THE INVENTION

The present invention relates to a composition comprising, by weight,the total being 100:

60 to 99.5% (preferably 70 to 93%) of at least one copolyamide offormula X/Y,Ar in which:

-   -   Y denotes the residues of an aliphatic diamine having from 8 to        20 carbon atoms,    -   Ar denotes the residues of an aromatic dicarboxylic acid,    -   X denotes either the residues of aminoundecanoic acid        NH₂—(CH₂)₁₀—COOH, of lactam-12 or of the corresponding amino        acid, or X denotes the unit Y,x, residue from the condensation        of the diamine with an aliphatic diacid (x) having between 8 and        20 carbon atoms, or X denotes the unit Y,I, residue from the        condensation of the diamine with isophthalic acid,

0.5 to 40% (preferably 7 to 30%) of at least one product chosen fromplasticizers, nanofillers, polyolefins, crosslinked polyolefins andadditives.

The intrinsic viscosity of the copolyamide is advantageously between 0.5and 2 and preferably between 0.8 and 1.8.

The advantage of these compositions is the low water uptake, which doesnot exceed 3% by weight.

Preferably, X/Y, Ar denotes:

-   -   11/10,T, which results from the condensation of aminoundecanoic        acid, 1,10-decanediamine and terephthalic acid,    -   12/12,T, which results from the condensation of lactam-12,        1,12-dodecanediamine and terephthalic acid,    -   10,10/10,T, which results from the condensation of sebacic acid,        1,10-decanediamine and terephthalic acid,    -   10,I/10,T, which results from the condensation of isophthalic        acid, 1,10-decanediamine and terephthalic acid.

The present invention also relates to structures comprising a layercomposed of the above composition. This structure is of use in preparingdevices for the storage or transfer of fluids, in particular inautomobiles. The invention also relates to these devices. These devicescan be tanks, pipes or containers. These structures can comprise otherlayers composed of other materials.

The compositions of the invention can replace rubbers or metals.

The compositions of the invention are also of use as materials forelectrical cables and can replace fluoropolymers.

The compositions of the invention are of use as materials forformulations comprising fillers: e.g. magnetic fillers. The compositionsof the invention then act as binder for fillers of this type.

DETAILED DESCRIPTION OF THE INVENTION

As regards the aromatic diacid, mention may be made of terephthalicacid, isophthalic acid, bibenzoic acid, naphthalenedicarboxylic acid,4,4′-biphenyldicarboxylic acid, bis(p-carboxyphenyl)methane,ethylenebis(p-benzoic acid), 1,4-tetramethylenebis(p-oxybenzoic acid),ethylenebis(para-oxybenzoic acid) or 1,3-trimethylenebis(p-oxybenzoicacid). Preferably, this is terephthalic acid; it is denoted by “T”.

As regards “Y”, the diamine can be an α,ω-diamine comprising a straightchain. It preferably has from 9 to 14 carbon atoms. According to apreferred form, this is 1,10-decanediamine. It can be branched or can bea mixture of a linear (straight-chain) diamine and of a brancheddiamine.

As regards “X”, and more particularly “x” in “Y,x”, this isadvantageously an aliphatic α,ω-diacid comprising a straight chain. Itpreferably has between 9 and 14 carbon atoms.

As regards the proportions of X, Y and Ar, Y and Ar are instoichiometric proportions or proportions very close to stoichiometric.

There is advantageously between 0.5 and 0.7 mol of X per 1 mol of Y (orone mole of Ar).

0.5 mol of X also means 0.5 mol of Y,x, that is to say 0.5 mol of Y and0.5 mol of x in the Y,x group. Likewise, 0.5 mol of X also means 0.5 molof Y,I, that is to say 0.5 mol of Y and 0.5 mol of I in the Y,I group.

If Y comprises a long chain, for example has at least of the order of 15to 18 carbon atoms, then the proportions of X can be very low, indeedeven zero. The copolyamide is reduced to Y,Ar. The invention alsorelates to the preceding compositions in which X/Y,Ar has become Y,Arand Y denotes the residues of an aliphatic diamine having from 10 to 20(preferably from 15 to 20 and better still from 18 to 20) carbon atoms.

If X/Y,Ar denotes 10,10/10,T, then the proportions of X can be higherand can be between 0.5 mol per 1 mol of Y and 1 mol per 0.05 mol of Y.

As regards the plasticizer, it is chosen from benzenesulphonamidederivatives, such as n-butylbenzenesulphonamide (BBSA),ethyltoluenesulphonamide or N-cyclohexyltoluenesulphonamide; esters ofhydroxybenzoic acids, such as 2-ethylhexyl para-hydroxybenzoate and2-decylhexyl para-hydroxybenzoate; tetrahydrofurfuryl alcohol esters orethers, such as oligoethoxylated tetrahydrofurfuryl alcohol; esters ofcitric acid or of hydroxymalonic acid, such as oligoethoxylatedmalonate. Mention may also be made of decylhexyl para-hydroxybenzoateand ethylhexyl para-hydroxybenzoate. A particularly preferredplasticizer is n-butylbenzenesulphonamide (BBSA).

As regards the nanofillers, this term is used to denote particles of anyshape, at least one of their dimensions being of the order of ananometre. Advantageously, these are lamellar exfoliable fillers. Inparticular, the lamellar exfoliable fillers are silicates and inparticular organophilic treated clays; these clays, which exist in theform of sheets, are rendered organophilic by insertion between thelatter of organic or polymeric molecules and are obtained in particularaccording to a process as disclosed in U.S. Pat. No. 5,578,672.

Preferably, the clays used are of the smectite type, either of naturalorigin, such as, in particular, montmorillonites, bentonites, saponites,hectorites, fluorohectorites, beidellites, stibensites, nontronites,stipulgites, attapulgites, illites, vermiculites, halloysites,stevensites, zeolites, fuller's earths and mica, or of synthetic origin,such as permutites.

Mention may be made, by way of example, of the organophilic claysdisclosed in U.S. Pat. No. 6,117,932. Preferably, the clay is modifiedwith an organic substance via an ionic bond with an onium ion having 6carbon atoms or more. If the number of carbon atoms is less than 6, theorganic onium ion is too hydrophilic and thus the compatibility with thepolymer (the blend of (A) and (B)) may decrease. Mention may be made, asexamples of organic onium ion, of hexylammonium ions, octylammoniumions, 2-ethylhexylammonium ions, dodecylammonium ions, laurylammoniumions, octadecylammonium (stearylammonium) ions, dioctyldimethylammoniumions, trioctylammonium ions, distearyldimethylammonium ions,stearyltrimethylammonium ions and ammonium laurate ions. It isrecommended to use a clay having the greatest possible contact surfacewith the polymer. The greater the contact surface, the greater theseparation of the clay flakes. The cation exchange capacity of the clayis preferably between 50 and 200 milliequivalents per 100 g. If thecapacity is less than 50, the exchange of the onium ions is inadequateand the separation of the clay flakes may be difficult. On the otherhand, if the capacity is greater than 200, the bonding strength of theclay flakes to one another is so strong that the separation of theflakes may be difficult. Mention may be made, as examples of clay, ofsmectite, montmorillonite, saponite, hectorite, beidellite, stibensite,nontronite, vermiculite, halloysite and mica. These clays can be ofnatural or synthetic origin. The proportion of organic onium ion isadvantageously between 0.3 and 3 equivalents of the ion exchangecapacity of the clay. If the proportion is less than 0.3, the separationof the clay flakes may be difficult. If the proportion is greater than3, decomposition of the polymer may occur. The proportion of organiconium ion is preferably between 0.5 and 2 equivalents of the ionexchange capacity of the clays. The nanofillers can be added to themonomers and can be present during the polymerization of the copolyamideor can be added after the polymerization.

As regards the crosslinked polyolefins, this phase can originate (i)from the reaction of two polyolefins having groups which react with oneanother, (ii) from maleicized polyolefins with a monomeric, oligomericor polymeric diamino molecule, (iii) or from one (or more) unsaturatedpolyolefin carrying unsaturation and which can be crosslinked, forexample, by the peroxide route. As regards the reaction of twopolyolefins, this crosslinked phase originates, for example, from thereaction:

-   -   of a product (A) comprising an unsaturated epoxide,    -   of a product (B) comprising an unsaturated carboxylic acid        anhydride,    -   optionally of a product (C) comprising an unsaturated carboxylic        acid or of an α,ω-aminocarboxylic acid.

As regards the crosslinked polyolefins, mention may be made, as exampleof product (A), of those comprising ethylene and an unsaturated epoxide.

According to a first form of the invention, (A) is either a copolymer ofethylene and of an unsaturated epoxide or a polyolefin grafted by anunsaturated epoxide.

As regards the polyolefin grafted by an unsaturated epoxide, the term“polyolefin” is understood to mean polymers comprising olefin units,such as, for example, ethylene, propylene, 1-butene or all otherα-olefin units. Mention may be made, by way of example, of

-   -   polyethylenes, such as LDPE, HDPE, LLDPE or VLDPE,        polypropylene, ethylene/propylene copolymers, EPRs        (ethylene/propylene rubber) or metallocene PEs (copolymers        obtained by single-site catalysis),    -   styrene/ethylene-butene/styrene (SEBS) block copolymers,        styrene/butadiene/styrene (SBS) block copolymers,        styrene/isoprene/styrene (SIS) block copolymers,        styrene/ethylene-propylene/styrene block copolymers or        ethylene/propylene/diene monomer (EPDM) terpolymers;    -   copolymers of ethylene with at least one product chosen from        salts or esters of unsaturated carboxylic acids or vinyl esters        of saturated carboxylic acids.

Advantageously, the polyolefin is chosen from LLDPE, VLDPE,polypropylene, ethylene/vinyl acetate copolymers or ethylene/alkyl(meth)acrylate copolymers. The density can advantageously be between0.86 and 0.965 and the melt flow index (MFI) can be between 0.3 and 40(in g/10 min at 190° C. under 2.16 kg).

As regards the copolymers of ethylene and of an unsaturated epoxide,mention may be made, for example, of copolymers of ethylene, of an alkyl(meth)acrylate and of an unsaturated epoxide or copolymers of ethylene,of a saturated carboxylic acid vinyl ester and of an unsaturatedepoxide. The amount of epoxide can be up to 15% by weight of thecopolymer and the amount of ethylene at least 50% by weight.

Advantageously, (A) is a copolymer of ethylene, of an alkyl(meth)acrylate and of an unsaturated epoxide.

Preferably, the alkyl (meth)acrylate is such that the alkyl has 2 to 10carbon atoms.

The MFI (melt flow index) of (A) can, for example, be between 0.1 and 50(g/10 min at 190° C. under 2.16 kg).

Examples of alkyl acrylate or methacrylate which can be used are inparticular methyl methacrylate, ethyl acrylate, n-butyl acrylate,isobutyl acrylate or 2-ethylhexyl acrylate. Examples of unsaturatedepoxides which can be used are in particular:

-   -   aliphatic glycidyl esters and ethers, such as allyl glycidyl        ether, vinyl glycidyl ether, glycidyl maleate, glycidyl        itaconate, glycidyl acrylate and glycidyl methacrylate, and    -   alicyclic glycidyl esters and ethers, such as 2-cyclohexen-1-yl        glycidyl ether, diglycidyl cyclohexene-4,5-dicarboxylate,        glycidyl cyclohexene-4-carboxylate, glycidyl        5-norbornene-2-methyl-2-carboxylate and diglycidyl        endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate.

According to another form of the invention, the product (A) is a producthaving two epoxide functional groups, such as, for example, bisphenol Adiglycidyl ether (BADGE).

Mention may be made, as examples of product (B), of those comprisingethylene and an unsaturated carboxylic acid anhydride.

(B) is either a copolymer of ethylene and of an unsaturated carboxylicacid anhydride or a polyolefin grafted by an unsaturated carboxylic acidanhydride.

The polyolefin can be chosen from the polyolefins mentioned above whichhas to be grafted by an unsaturated epoxide.

Examples of unsaturated dicarboxylic acid anhydrides which can be usedas constituents of (B) are in particular maleic anhydride, itaconicanhydride, citraconic anhydride and tetrahydrophthalic anhydride.

Mention may be made, as examples, of copolymers of ethylene, of an alkyl(meth)acrylate and of an unsaturated carboxylic acid anhydride andcopolymers of ethylene, of a saturated carboxylic acid vinyl ester andof an unsaturated carboxylic acid anhydride.

The amount of unsaturated carboxylic acid anhydride can be up to 15% byweight of the copolymer and the amount of ethylene at least 50% byweight.

Advantageously, (B) is a copolymer of ethylene, of an alkyl(meth)acrylate and of an unsaturated carboxylic acid anhydride.Preferably, the alkyl (meth)acrylate is such that the alkyl has 2 to 10carbon atoms.

The alkyl (meth)acrylate can be chosen from those mentioned above.

The MFI of (B) can, for example, be between 0.1 and 50 (g/10 min at 190°C. under 2.16 kg).

According to another form of the invention, (B) can be chosen fromaliphatic, alicyclic or aromatic polycarboxylic acids or their partialor complete anhydrides.

Mention may be made, as examples of aliphatic acids, of succinic acid,glutaric acid, pimelic acid, azelaic acid, sebacic acid, adipic acid,dodecanedicarboxylic acid, octadecanedicarboxylic acid, dodecenesuccinicacid and butanetetracarboxylic acid.

Mention may be made, as examples of alicyclic acids, ofcyclopentanedicarboxylic acid, cyclopentanetricarboxylic acid,cyclopentanetetracarboxylic acid, cyclohexanedicarboxylic acid,cyclohexanetricarboxylic acid, methylcyclopentane-dicarboxylic acid,tetrahydrophthalic acid, endo-methylenetetrahydrophthalic acid andmethyl-endo-methylenetetrahydrophthalic acid.

Mention may be made, as examples of aromatic acids, of phthalic acid,isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid orpyromellitic acid.

Mention may be made, as examples of anhydrides, of the partial orcomplete anhydrides of the above acids.

Use is advantageously made of adipic acid.

It would not be departing from the scope of the invention if a portionof the copolymer (B) is replaced by an ethylene-acrylic acid copolymeror an ethylene-maleic anhydride copolymer, the maleic anhydride havingbeen completely or partially hydrolysed. These copolymers can alsocomprise an alkyl (meth)acrylate. This portion can represent up to 30%of (B).

With regard to the product (C) comprising an unsaturated carboxylicacid, mention may be made, as examples, of the products (B) completelyor partly hydrolysed. (C) is, for example, a copolymer of ethylene andof an unsaturated carboxylic acid and advantageously a copolymer ofethylene and of (meth)acrylic acid.

Mention may also be made of the copolymers of ethylene, of an alkyl(meth)acrylate and of acrylic acid.

These copolymers have an MFI of between 0.1 and 50 (g/10 min at 190° C.under 2.16 kg).

The amount of acid can be up to 10% by weight and preferably 0.5 to 5%.The amount of (meth)acrylate is from 5 to 40% by weight.

(C) can also be chosen from α,ω-aminocarboxylic acids, such as, forexample, NH₂—(CH₂)₅COOH, NH₂—(CH₂)₁₀COOH and NH₂(CH₂)₁₁—COOH andpreferably aminoundecanoic acid.

The proportion of (A) and (B) necessary to form the crosslinked phase isdetermined according to the usual rules of the art by the number ofreactive functional groups present in (A) and in (B).

For example, in the crosslinked phases comprising (C) chosen fromα,ω-aminocarboxylic acids, if (A) is a copolymer of ethylene, of analkyl (meth)acrylate and of an unsaturated epoxide and (B) a copolymerof ethylene, of an alkyl (meth)acrylate and of an unsaturated carboxylicacid anhydride, the proportions are such that the ratio of the anhydridefunctional groups to the epoxy functional groups is in the region of 1.

The amount of α,ω-aminocarboxylic acid is then from 0.1 to 3% andpreferably 0.5 to 1.5% of (A) and (B).

As regards (C) comprising an unsaturated carboxylic acid, that is to say(C) being chosen, for example, from ethylene/alkyl(meth)acrylate/acrylic acid copolymers, the amount of (C) and (B) can bechosen so that the number of acid functional groups and of anhydridefunctional groups is at least equal to the number of epoxide functionalgroups and, advantageously, products (B) and (C) are used such that (C)represents 20 to 80% by weight of (B) and preferably 20 to 50%.

It would not be departing from the scope of the invention if a catalystwere added.

These catalysts are generally used for the reactions between the epoxygroups and the anhydride groups.

Mention may in particular be made, among the compounds capable ofaccelerating the reaction between the epoxy functional group present in(A) and the anhydride or acid functional group present in (B), of:

-   -   tertiary amines, such as dimethyllaurylamine,        dimethylstearylamine, N-butylmorpholine,        N,N-dimethylcyclohexylamine, benzyldimethylamine, pyridine,        4-(dimethylamino)pyridine, 1-methylimidazole,        tetramethylethylhydrazine, N,N-dimethylpiperazine,        N,N,N′,N′-tetramethyl-1,6-hexanediamine or a mixture of tertiary        amines having from 16 to 18 carbons and known under the name of        dimethyltallowamine    -   1,4-diazabicyclo[2.2.2]octane (DABCO)    -   tertiary phosphines, such as triphenylphosphine    -   zinc alkyldithiocarbamates.

The amount of these catalysts is advantageously from 0.1 to 3% andpreferably 0.5 to 1% of (A)+(B)+(C).

As regards the noncrosslinked polyolefins, mention may be made of thepolyolefins described in the preceding section and intended to begrafted by reactive groups. Mention may also be made of the products (A)or (B) or (C) of the preceding section but used alone in order not tocrosslink. Mention may be made, by way of examples, of the EPR or EPDMelastomers, it being possible for these elastomers to be grafted inorder to make it easier to render them compatible with the copolyamide.Mention may also be made of acrylic elastomers, for example those of theNBR, HNBR or X-NBR type.

As regards the preparation of the compositions of the invention, use maybe made of any conventional process for the synthesis of polyamides andcopolyamides.

The compositions according to the invention can additionally include atleast one additive chosen from:

-   -   dyes;    -   pigments;    -   brighteners;    -   antioxidants;    -   flame retardants;    -   UV stabilizers;    -   nucleating agents.

1. Composition comprising, by weight, the total being 100: 60 to 99.5%of at least one copolyamide of formula X/Y,Ar in which there is between0.5 and 0.7 mol of X per 1 mol of Y, and in which: Y denotes theresidues of 1,10-decanediamine, Ar denotes the residues of terephthalicacid, X denotes the residue of aminoundecanoic acid NH₂—(CH₂)₁₀—COOH,the unit Y,I residue from the condensation of the diamine (Y) withisophthalic acid, wherein said composition is a flexible semiaromaticcopolyamide; 0.5 to 40% of at least one product chosen from nanofillers,polyolefins, crosslinked polyolefins and additives.
 2. Compositionaccording to claim 1, in which the proportion of the copolyamide is from70 to 93% for 7 to 30% of at least one product chosen from nanofillers,polyolefins, crosslinked polyolefins and additives.
 3. Compositionaccording to claim 1, in which the intrinsic viscosity of thecopolyamide is between 0.5 and
 2. 4. Composition according to claim 3,in which the intrinsic viscosity of the copolyamide is between 0.8 and1.8.
 5. Composition according to claim 1, in which Y and Ar are instoichiometric proportions or proportions very close to stoichiometric.6. Composition according to claim 1 in which X/Y,Ar denotes 11/10,T,which results from the condensation of aminoundecanoic acid,1,10-decanediamine and terephthalic acid.
 7. Composition according toclaim 1, wherein said additive comprises one or more additives selectedfrom the group consisting of dyes, pigments, brighteners, antioxidants,flame retardants, UV stabilizers, and nucleating agents.
 8. Structurecomprising a layer composed of the composition according to claim
 1. 9.Formulation comprising fillers and binder, wherein said binder comprisesof the composition according to claim 1.